Burner

ABSTRACT

A burner having opposed walls defining a combustion chamber is disposed in an airstream with the combustion chamber opening downstream. At the upstream end of the walls, orifices of a gas manifold open into the combustion chamber. The opposed walls are each composed of a plurality of segments which are secured together along side flanges so that the intervening bight portions of the segments form a continuous wall surface. Slots extend across the segments, terminating at the side flanges thereof, and the slots on some of the opposed wall segments are staggered with respect to one another and with respect to the orifices so that air introduced through them forms vortices within the combustion chamber about the orifices. Outer walls form air supply chambers with the back faces in the combustion chamber walls and the air supply chambers are fed with combustion air from the airstream through an inlet opening upstream.

nited States Patent Frederick A. Kramer, Jr. 2040 Conway Road, St. LouisCounty, Mo.

[72] inventor [56] References Cited UNITED STATES PATENTS Re25,6267/1964 Yeo et a1. 431/352 X 3,265,376 8/1966 Spielman 263/19 A ABSTRACT:A burner having opposed walls defining a combustion chamber is disposedin an airstream with the combustion chamber opening downstream. At theupstream end of the walls, orifices of a gas manifold open into thecombustion chamber. The opposed walls are each composed of a pluralityof segments which are secured together along side flanges so that theintervening bight portions of the segments form a continuous wallsurface. Slots extend across the segments, terminating at the sideflanges thereof, and the slots on some of the opposed wall segments arestaggered with respect to one another and with respect to the orificesso that air introduced through them forms vortices within the combustionchamber about the orifices. Outer walls form air supply chambers withthe back faces in the combustion chamber walls and the air supplychambers are fed with combustion air from the ail-stream through aninlet opening upstream.

atented Dec; 28, 1971 3,630,499

2 Sheets-Sheet 1 Patented Dec. 28, 1971 3,630,499

2 Sheets-Sheet 2 Fl (3 6 1 graze/1467.2

BURNER BACKGROUND OF THE INVENTION This invention relates in general toheating devices and more particularly to gas burners for heating movingairstreams.

Perhaps the most efficient method of heating air with natural gas, aswell as other combustible gases, is to dispose a flame-produeing burnerdirectly in an airstream so that the heat of the flame enters theairstream without passing through some intervening medium. Heatingdevices'of this type are normally disposed in duct work for supplyingso-called makeup air for buildings, for heating air used in air curtainconstructions, for supplying heated air for building heat, and forheating air introduced into ovens and other drying apparatus. Currentburners designed for such applications have not proved entirelysatisfactory. In the first place, many are subject to having theirflames extinguished when the velocity of the airstrearn experiences arapid change. For example, in many burners the flame is projected aconsiderable distance downstream from the burner envelop where the airin the duct flows at high velocities, for the downstream position iswhere the air and the gas become mixed sufficiently for combustion.Should the air experience sudden changes in velocity, i.e., turbulence,the chances of the flame burning incompletely are quite high. The sameproblem exists in turbulent air patterns. Secondly, by reason of thefact that the position of the flame in the burner envelop is dependenton the velocity of the air in the duct and the fuel flow rate, severaligniting devices must be employed to ignite the aingas mixture so thatat least one will be in the position at which the gas and air are mixedsufficiently to permit combustion. That position, of course, isdependent on the velocity of the airstream in the duct as previouslynoted. Similarly, several flame-sensing probes must also be utilized. Inaddition, since the burners can be operated intermittently, theirvarious components are subjected rcpeatedly to the effects of thermalexpansion. In the case of burners having sidewalls provided withair-conducting orifices, fatigue cracks often develop at the orificesand these cracks eventually weaken and distort the entire burnerassembly. Moreover, many burners do not operate adequately over a widerange of gas flows and, therefore, they do not have the capability ofproviding precise temperature control for the airstream. On thecontrary, they either overheat or underheat the airstream.

One of the principal objects of the present invention is to provide aburner for maintaining precise heating control over an airstream.Another object is to provide a bumer of the type stated which burns gascompletely when subjected to turbulent air patterns or varying high-airvelocities. An additional object is to provide a burner. of the typewhich thoroughly mixes the entering combustible gas and the combustionis complete and produces only a minimal amount of carbon monoxide. Stillanother object is to provide a burner construction which can withstandrepeated expansions and contrac-- tions due to intermittent operationwithout failure or distortion. Yet another object is to provide a burnerwhich is simple and rugged in construction and requires only one flameigniter and sensing probe. Still another object is to provide anadjustable air metering'arrangement for combustion air to meet varyingair velocity conditions. These and other objects and advantages willbecome apparent hereinafter.

SUMMARY OF THE INVENTION The present invention is embodied in a burnerhaving apertured walls which define a combustion chamber and closuremeans sheathing those apertured walls and forming an air supply chambertherewith. The invention also includes segmented combustion chamberwalls, the individual segments of which are attached along integrallyformed side flanges. The invention also consists in .the parts and inthe arrangements DESCRIPTION OF THE DRAWINGS In the accompanyingdrawings which form part of the specification and wherein like numeralsand letters refer to like parts wherever they occur:

FIG. 1 is an elevational view, partially broken away and in section, ofa fan, duct, and a burner constructed in accordance with the presentinvention; I

FIG. 2 is a sectional view taken along line 2--2 of FIG. 1,

FIG. 3 is a sectional view taken along line 3--3 of FIG. 2,

FIG. 4 is a fragmentary perspective view showing two adjacent wallsegments forming part of the present invention,

FIG. 5 is a sectional view taken along line 5-5 of FIG. 3,

and

FIG. 6 is an end view of the combustion chamber showing the air swirlsinduced about the gas orifices of the manifold.

DETAILED DESCRIPTION Referring now in detail to the drawings, in FIG. 1,the numeral 2 designates a burner which is mounted in a duct 4 adjacentto the discharge of a centrifugal fan 6. The burner 2 may be mountedeither on the upstream or downstream side of the fan 6, the latter beingmore desirable since it does not subject the fan 6 to excessive heatingand further permits the fan 6 to handle a greater quantity of air interms of weight. The burner 2 is suspended from the upper wall of theduct 4 by means of a pair of straps 8, and is further stabilised withinthe duct 4 by a gas supply pipe 10 which projects through the upper wallof the duct 4.

The burner 2 includes a pair of sidewalls l2 and 14 interconnected by apair of transversely extending combustion chamber walls 16 and 18 whichconverge toward a mainfold 20 in the formation of a forwardly divergentcombustion chamber 22. More specifically, the manifold 20 is preferablyan elongated casting interposed between the sidewalls l2 and I4 andhaving a longitudinally extending channel 24 closed at each end by endplates 26 which are held against the outwardly presented faces of thesidewalls l2 and 14 by means of a stove rod 28 extending through thechannel 24. On its upwardly presented face the manifold 20 is providedwith a cylindrical boss 30 containing a threaded bore which opens intothe channel 24 at its inner end and receives the end of the gas supplypipe 10 at its outer end. On its forwardly presented side the manifold20 is further provided with a transversely extending ridgelikeembossment 32 through which a plurality of gas orifices 34 open into thecombustion chamber 22. The orifices 34 are equally spaced in a singleline across the embossment 34 and at their rear ends open into thechannel 24 so that the orifices 34 establish communication between thechannel 24 and the combustion chamber 22.

Each combustion chamber wall 16 or 18 is composed of rear, forward, andintermediate channellike wall segments 36, 38 and 40, respectively,(FIGS. 3, 4, and 4, which extend between the sidewalls l2 and 14parallel to the manifold 20. Each channellike segment 36, 38, or 40, inturn, has side flanges 42 connected by a flat bight or face portion 44which is turned outwardly at its ends in the provision of end flanges46. The side flanges 42 of the wall segments 36, 38 and 40 are providedwith equally spaced aligned circular apertures 48 (FIG. 6) which areconnected through the bight portions by slots 50 so that the structuralcontinuity of the wall segments 36, 38 and 40 is maintained solelythrough the outer edges of their side flanges 42. One side flange 42 oneach of the inner and outer wall segments 36 and 38 is spot welded to adifferent side flange 42 on the corresponding intermediate wall segment40 such that the bight portions 44 and end flanges 46 of all three ofthe joined wall segments are coplanar. The end flanges 46 are similarlyspot welded to the inwardly presented faces of the sidewalls l2 and 14and, accordingly, maintain the combustion chamber walls 16 and 18 rigidat the proper angle and combinations of parts hereinafter described andclaimed. of divergence.

The slots 50 on the adjacent wall segments 38 and 40 are equally spaced(FIGS. 2 and 5), the spacing being equivalent to the spacing between thegas orifices 34, but are staggered with respect to one another. Theslots 50 in the intermediate wall segments 40 are further staggered withrespect to the slots 50 in the rear segment 36, so that no slot 50 iscontinuous beyond its particular wall segment. Moreover, the slots 50 onthe forward and intermediate wall segments 38 and 40 of the combustionchamber wall 16 are presented directly opposite the corresponding slots50 in the forward and intermediate wall segments 38 and 40 of the wall18. The slots 50 in the intennediate wall segment 40, furthen'nore,align with the orifices 34, making the slots 50 in the forward wallsegment 38 offset with respect to those orifices 34. The slots 50 of therear wall segments 36 of each wall 16 and 18, on the other hand, arespaced apart a distance equal to twice the spacing between the orifices34 and are staggered with respect to those orifices 34 as well as withrespect to themselves. Consequently, each slot 50 in one of the rearwall segments 40 opens into the combustion chamber 22 between adjacentorifices 34 and opposite to a solid bight portion 44 on the oppositewall segment 36. This staggering of the slots 50 in the opposed rearwall segments 36 generates a vortex about each one of the orifices 34when air is introduced into the combustion chamber 22 through thoseslots 50 (FIG. 6).

Finally, the rearmost side flanges 42 on the rear wall segments 36 aresomewhat wider than the remaining side flanges 42 and abut against theforwardly presented face of the manifold 20 on each side of theridgelike embossment 32 thereon (FIG. 3), so that the embossment 32 isin effect disposed between the rear ends of the combustion chamber walls16. Those flanges 42, moreover, extend laterally beyond the side facesof the manifold 20 where they receive stove bolts 52 which pass alongthe sides of the manifold 20 and through a baffle plate 54 abutting therearwardly presented face of the manifold 20. By means of thisconstnrction, the manifold 20 is held securely against the rearmost sideflanges 42 on the combustion chamber walls 16 and 18.

The edges of the sidewalls l2 and 14 are turned inwardly in theformation of mounting flanges 56 and mounting tabs 58 (H68. 3 and 5) thefonner of which are presented outwardly from the clamping plate 54 andmanifold 20 as well as from the outer edges of the side flanges 42,excepting the foremost side flange 42 with which the mounting flanges 56align. The mounting tabs 58, on the other hand, are oblique to themounting flanges 56 and are located to the rear of the manifold 20. Themounting flanges 56 and tabs 58 are clamped to outer walls 60 and 62which are presented outwardly from the combustion chamber walls 16 and18, respectively, in the formation of air supply chambers 64. At theirforward ends the outer walls 60 and 62 are provided with inwardly turnedfront flanges 66 which underlie the foremost side flanges 42 on thecombustion chamber walls 16 and 18. At their opposite ends the walls 60and 62 turn inwardly, fonning oblique portions 68 which are connectedwith tabs 58, and beyond the tabs 58 the oblique portions 68 merge intoinwardly extending lips 70 which are located in spaced parallel relationto one another and further terminate prior to the clamping plate 54 atthe rear of the manifold 20 in the fonnation of an inlet 65. Themetering air inlet 65 opens upstream into the airstream of the duct 4and diverts a portion of the air from the airstream into the air supplychambers 64.

The parts 60, 68, and 70 form metering air inlet 65 and the chamberdefined by baffle plate 54 and the parts 60, 68 and 70 acts to reduceturbulent intake air to a uniform smooth flow of air for combustion. Thelip 70 preferably is formed as a separate part and includes a slot 71through which a screw 71A fastens the lip 70 to the portions 68. Thusthe opening 65 can be adjusted to meter various amounts of combustionairflow into the burner.

The sidewall 12 is further fitted with a pair of threaded sockets 72 and74, the former of which is located centrally of socket 72 is a sparkplug 76 having its spark gap located within the combustion chamber 22.The other threaded socket 74 carries a conventional flame probe 78 whichalso projects into the combustion chamber 22 beyond the plug 76 forsensing the presence or absence of a flame in the chamber 22.

The gas supply pipe 10 is connected through suitable valving (not shown)to a source of natural gas or some other combustible gas, and thatvalving has the capability of controlling the amount of gas flowingthrough the pipe 10 into the manifold 20. The valving also contains ashut-off connected with the flame probe 78 for shutting off the flow ofgas should the flame be extinguished. Finally, the spark plug 76 isconnected to a suitable electrical source capable of supplyingsufficient voltage to cause a spark to jump across the gap of the plug76. Of course, the shut-off valve should not block the flow of gas tothe supply pipe 10 when a high voltage potential is being impressedacross the gap of the plug 76 so that a combustible gas-air mixture willbe in the chamber when the spark is produced.

OPERATION To ignite the burner 2, a high-electrical potential isimpressed across the gap of the spark plug 76 while at the same time acombustible gas is introduced into the manifold 20 through the supplypipe 10. That gas flows into the channel 24 and is discharged into thecombustion chamber 22 through the orifices 34. The combustion air forthe combustible gas introduced into the combustion chamber 22 is derivedfrom the airstream flowing in the duct 4. In particular, the air inlet65, being disposed in the airstream, diverts a portion of the airstreaminto the air supply chambers 64. Since the air can only escape from thechambers 64 through the relatively small area of the slots 50,stagnation occurs within the chambers 64 with a corresponding increasein pressure. Accordingly, the pressure of the air within the air supplychambers 64 is somewhat greater than the pressure existing in thecombustion chamber 22, and by reason of this fact, the combustion airfrom the chambers 64 discharges into the combustion chamber 22 throughthe slots 50.

Inasmuch as the slots 50 in the opposed rear wall segments 36 arestaggered with respect to one another and are further interposed betweenthe orifices 34, the combustion air entering the combustion chamber 22immediately forwardly of the manifold 20 creates elongated gentlevortices around the orifices 34 (FIG. 6). More specifically, thecombustion air following into the chamber 22 through a particular slot50 in one of the rear wall segments 36 passes between two orifices 34and strikes the bight portion of the opposite wall segment 36, and in sodoing the air difi'uses laterally in both directions and joins theairstreams following into the chamber 22 from the two adjacent slots 50in that opposite wall segment 36. This effect is repeated at each slot50 in the rear wall segments 36 and continues along the entire length ofthe ridgelike embossment 32 on the manifold 20. The combustible gas isdirected by the orifices 34 into the centers of these elongated vorticesand is immediately drawn into the vortices where the gas is gently anduniformly mixed with the combustion air. More combustion air isintroduced into the combustion chamber 22 through the slots 50 in theintermediate and forward wall segments 40 and 38 and this discharge ofair creates turbulence in the chamber 52 and insures complete mixing ofthe combustible gas and the combustion air.

The spark across the gap of the spark plug 76 remains long enough toignite the mixture of combustible gas and combustion air after which thespark plug 76 is deenergized since the resulting flame in the combustionchamber 22 is self sustaining. Should the flame, for some reason, becomeextinguished, the flame probe 78 will sense the absence of a flame andwill halt the flow of the combustible gas into the manifold 20.

Since the outwardly facing sides of the combustion chamber the ends ofthe rear wall segments 36, and threaded into that walls 16 and 18 arenot exposed to the free-flowing airstream in the duct 4 as is true ofsome burners of current manufacture, but on the contrary are exposed tothe relatively stagnant air in the combustion air supply plenums M, thecombustion air enters the combustion chamber 22 at moderate uniformvelocities, even when the velocity of the airstream within the duct 4remains high. Consequently, the flame within the combustion chamberimmediately forward of the manifold 20. The flame burns completelywithin the combustion chamber 22 so no additional combustion air isneeded beyond the end of the combustion chamber when the airstream inthe duct reaches high velocities as is true of those burners of currentmanufacture which have their apertured combustion chamber walls exposedto the free flowing airstream. Since the position of the flame remainssubstantially fixed within the combustion chamber 22 irrespective of thevelocity of the airstream, only one spark plug 76 and flame probe 78 arenecessary.

The burner 2 may be operated over a wide range of gas flow rates, andconsequently, has a high tum-down capability. When the flow rate of thecombustible gas out of the orifices 341 is low, the flame will berelatively small and confined generally to the area of the combustionchamber 22 bounded by the rear wall segments 36. The vortex effect isstill maintained since the staggered slots 50 are in the opposed rearwall segments 36 which are located immediately forwardly of the manifold20. The excess combustion air escapes into the freeflowing airstreamthrough the slots 50in the intermediate and front wall segments 40 and38 which are located ahead of the flame in this instance.

When the gas flow rate is increased, the length of the flame increasesand the additional combustion air required for the additional gas issupplied through the slots 50 in the intermediate and front wallsegments 40 and 38. Even at high-gas flow rates, the rear terminus ofthe flame remains adjacent to the ridgelike embossment 32 on themanifold 20. In any event, the combustion air is gently and uniformlymixed with the combustible gases so that the ensuing combustion iscomplete and produces only minimal traces of carbon monoxide.

By reason of the fact that the structural continuity of the extendedcombustion chamber walls 16 and 18 is maintained through the sideflanges 42 of their wall segments 36, 38 and $0, the bight portions 44of the wall segment 36, 38 and 40, which portions actually form thesurfaces bounding the combustion chamber 22, are not subjected to theextreme stresses which would otherwise be produced due to temperaturedifferentials in the wall. Thus, the bight portions 44 are, in effect,isolated from the one another and can be maintained at differenttemperatures without inducing extreme structural stresses in the walls16 and 18. Accordingly, fatigue cracks will not emanate from the slots50, even after extended periods of use and repeated firings andshutdowns. The thermal expansion which does occur is along the sideflanges 42 and inasmuch as these flanges 42 are relatively narrow, thechances of a large temperature differential and corresponding stressesacross one are indeed remote. The presence of the slots 50 furtherretards warpage of the walls 116 and 18.

Thus it is seen that the foregoing invention achieves the objects andadvantages sought therefor which include the followmg:

l. A multistage burner with mixing of air and gas allowing combustionand burning at the point where the gas enters the burner within thefirst stage (the base of the jets) at all gas flow rates and additionalcombustion air being added to the fire in the later stages for higherfires.

2. A smooth flow of metered combustion air using an adjustable meteringdevice and plenum.

3. The fan being located immediately before the burner resulting in acompact construction while still maintaining good burningcharacteristics.

4. Complete combustion within the burner so that combustion air from theduct is not required beyond the end of the burner at high fire.

5. The use of slots in all stages for strength and burningcharacteristics and to eliminate expansion and contraction problems.

6. Adjustment of the flame by varying the amount of gas entering theburner.

7. The provision of a unit in which the fan and burner can be mounted ina cabinet for a horizontal straight through design or with a downturn toform an air curtain construction.

This invention is intended to cover all changes and modifications of theexample of the invention herein chosen for purposes of the disclosurewhich do not constitute departures from the spirit and scope of theinvention.

What is claimed is:

l. A burner comprising a pair of opposed walls defining a combustionchamber, each of the opposed walls including an equal number of wallsegments with corresponding wall segments of the two walls being ofequal size and located directly across the combustion chamber from oneanother, each of the wall segments having face portions and connectingmeans located at the sides of the face portions, the connecting means ofadjacent wall segments being secured to one another such that the faceportions of the connected wall segments form a generally continuoussurface which is presented toward the combustion chamber, the wallsegments being provided with slots for admitting air to the combustionchamber, the slots extending across the face portions of theirrespective wall segments and the slots in adjacent wall segments beingstaggered relative to one another so that a slot is not continued beyonda wall segment in which it is located; and a manifold at one end of theopposed walls and located adjacent to one of the wall segments for eachof the walls, the manifold having longitudinally spaced orifices whichopen into the combustion chamber for introducing a combustible gas intothe combustion chamber; the slots of the two wall segments locatedadjacent to the manifold being staggered relative to each other andrelative to the orifices of the manifold so that air entering thecombustion chamber through those slots creates vortices about thecombustible gas as that gas is introduced into the combustion chamberthrough the orifices.

2. A burner comprising a manifold connected to a source of combustiblegas and having a plurality of orifices through which the combustible gasis discharged from the manifold, the orifices being spaced generally oneafter another; and a pair of opposed walls extending away from themanifold and partially defining a combustion chamber into which theorifices open so that the combustible gas is introduced into thecombustion chamber, each wall comprising a plurality of wall segmentsarranged side-by-side and each wall segment including a face portionpresented toward the combustion chamber and a connecting portionconnected to the face portion along at least each side thereof which isadjacent to another wall segment, each connecting portion beingpresented at an angle with respect to the face portion to which it isconnected and projecting away from the face portion, the connectingportions of adjacent wall segments being joined together so that theopposed walls are unitary, the wall segments having apertures in theface portions thereof for admitting air to the combustion chamber, eachaperture extending from one side of the wall segment in which it islocated to the other side of that wall segment and terminating at aconnecting portion, whereby the face portions of the wall segments arenot subjected to extreme stresses when a temperature differential existsin the walls.

3. A, burner according to claim 2 wherein the connecting portions areformed integral with the face portions and project outwardly away fromthe combustion chamber.

4. A burner according to claim 3 wherein the face portions for adjacentwall segments are flush.

5. A burner according to claim 3 wherein the wall segments extend in thesame general direction as the manifold so that the wall segments foreach wall are arranged one after another away from the manifold.

6. A burner according to claim 5 wherein the apertures are slots.

7. A burner according to claim 6 wherein the slots in the face portionsof the two wall segments located closest to the manifold are staggeredwith respect to each other and also with respect to the orifices of themanifold, whereby the air admitted into the combustion chamber throughthose slots creates vortices about the combustible gas as that gas isintroduced into the combustion chamber through the orifices.

8. A burner according to claim 2 wherein each of the wall segments isprovided with a flange formed integral with its face portion along thesides thereof and turned outwardly away from the combustion chamber;wherein the flanges along the juxtaposed sides of adjacent wall segmentsare joined and constitute the connecting portions; and wherein theapertures are slots which terminate in the flanges.

9. A burner according to claim 6 wherein the connecting portions on thewall segments are outwardly turned flanges extending along the sides ofthe face portions; and wherein the slots extend at least to the flanges.

10. A burner according to claim 7 wherein the slots in adjacent wallsegments are staggered relative to one another so that a slot is notcontinued beyond the wall segment in which it is located.

11. A burner according to claim 1 wherein the opposing walls divergeaway from the manifold and are connected at their sides by sidewalls.

12. A burner according to claim 8 wherein the slots terminate atenlarged cutouts formed in the side flanges of the wall segments.

13. A burner according to claim 2 wherein the burner is disposed withinan airstream with its combustion chamber opening downstream; wherein aclosure encloses the outwardly presented faces of the opposed sidewallsand form combustion air supply plenums therewith; and wherein the airsupply plenum are supplied with air from the airstream through at leastone air-metering means which opens upstream in the airstream.

14. In a duct through which a moving stream of air flows; an improvedburner for heating the air flowing in the duct; said burner comprising amanifold connected to a source of combustible gas and having orificesthrough which the combustible gas is discharged from the manifold;opposed combustion chamber walls extending away from the manifold anddefining a combustion chamber having one end located downstream from theother end relative to the stream of air flowing in the duct, the opposedcombustion chamber walls at the upstream end of the combustion chamberbeing presented adjacent to the manifold on opposite sides of themanifold orifices so that the orifices open into the combustion chamber,the downstream end of the combustion chamber opening into the duct andfacing downstream therein, the combustion chamber walls having aperturestherein; outer walls presented outwardly from the combustion chamberwalls and forming a closure therewith which defines a supply plenum, thesupply plenum communicating with the combustion chamber through theapertures in the combustion chamber walls; and inlet means associatedwith the outer walls and defining an opening which faces upstream in theduct and is exposed directly to the airstream therein so that the airflowing in the duct will enter the opening, the opening communicatingwith the air supply plenum, whereby the air which enters the openingpasses into the plenum from which it is discharged into the combustionchamber through the apertures on the combustion chamber walls, theaperture being elongated slots extending in the same general directionthat the combustible gas is introduced into the combustion chamber, andat least some of the slots in one wall being staggered with respect toslots in the opposite wall; the orifices being arranged inlongitudinally spaced relation along the manifold; the slots which arelocated in those portions of the opposed combustion chamber walls whichare adjacent to the orifices being staggered with respect to theorifices so that elongated vortices are induced about the axes of theorifices.

15. In a duct through which a moving stream of air flows; an improvedburner for heating the air flowing in the duct; said burner comprising amanifold connected to a source of combustible gas and having orificesthrpu which the combustible gas IS discharged from the mamfo d; opposedcombustion chamber walls extending away from the manifold and defining acombustion chamber having one end located downstream from the other endrelative to the stream of air flowing in the duct, the opposedcombustion chamber walls at the upstream end of the combustion chamberbeing presented adjacent to the manifold on opposite sides of themanifold orifices so that the orifices open into the combustion chamber,the downstream end of the combustion chamber opening into the duct andfacing downstream therein, the combustion chamber walls having aperturestherein; outer walls presented outwardly from the combustion chamberwalls and forming a closure therewith which defines a supply plenum, thesupply plenum communicating with the combustion chamber through theapertures in the combustion chamber walls; and inlet means associatedwith the outer walls and defining an opening which faces upstream in theduct and is exposed directly to the airstream therein so that the airflowing in the duct will enter the opening, the opening communicatingwith the air supply plenum, whereby the air which enters the openingpasses into the plenum from which it is discharged into the combustionchamber through the apertures on the combustion chamber walls, whereinthe inlet means comprises at least one member which is shiftablerelative to the outer walls so that the size of the inlet opening can bevaried.

i t I i t 3,630,499 December 28, 1971 Patent No. Dated Frederick A.Kramer, Jr. Inventor(s) It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 2, line 56 "4" should be "5" Column 5, line 6, "remains" shouldbe inserted before "withirfi Column 5, line 47, cancel the" Column 8,line 18 add "to each other; and the staggered slots also being staggeredwith respect Signed and sealed this 11th day of July 1972.

(SEAL) Attest:

EDWARD I LI'LETCHER, JR. ROBERT GOTTSCHALK Attesting OfficerCommissioner of Patents FORM PO-105Q (10-69) I I uscoMM-DC 50376 3 9 IU,$. GOVERNMENT PRINTING OFFICE 1 I969 ()"365'334

1. A burner comprising a pair of opposed walls defining a combustionchamber, each of the opposed walls including an equal number of wallsegments with corresponding wall segments of the two walls being ofequal size and located directly across the combustion chamber from oneanother, each of the wall segments having face portions and connectingmeans located at the sides of the face portions, the connecting means ofadjacent wall segments being secured to one another such that the faceportions of the connected wall segments form a generally continuoussurface which is presented toward the combustion chamber, the wallsegments being provided with slots for admitting air to the combustionchamber, the slots extending across the face portions of theirrespective wall segments and the slots in adjacent wall segments beingstaggered relative to one another so that a slot is not continued beyonda wall segment in which it is located; and a manifold at one end of theopposed walls and located adjacent to one of the wall segments for eachof the walls, the manifold having longitudinally spaced orifices whichopen into the combustion chamber for introducing a combustible gas intothe combustion chamber; the slots of the two wall segments locatedadjacent to the manifold being staggered relative to each other andrelative to the orifices of the manifold so that air entering thecombustion chamber through those slots creates vortices about thecombustible gas as that gas is introduced into the combustion chamberthrough the orifices.
 2. A burner comprising a mAnifold connected to asource of combustible gas and having a plurality of orifices throughwhich the combustible gas is discharged from the manifold, the orificesbeing spaced generally one after another; and a pair of opposed wallsextending away from the manifold and partially defining a combustionchamber into which the orifices open so that the combustible gas isintroduced into the combustion chamber, each wall comprising a pluralityof wall segments arranged side-by-side and each wall segment including aface portion presented toward the combustion chamber and a connectingportion connected to the face portion along at least each side thereofwhich is adjacent to another wall segment, each connecting portion beingpresented at an angle with respect to the face portion to which it isconnected and projecting away from the face portion, the connectingportions of adjacent wall segments being joined together so that theopposed walls are unitary, the wall segments having apertures in theface portions thereof for admitting air to the combustion chamber, eachaperture extending from one side of the wall segment in which it islocated to the other side of that wall segment and terminating at aconnecting portion, whereby the face portions of the wall segments arenot subjected to extreme stresses when a temperature differential existsin the walls.
 3. A burner according to claim 2 wherein the connectingportions are formed integral with the face portions and projectoutwardly away from the combustion chamber.
 4. A burner according toclaim 3 wherein the face portions for adjacent wall segments are flush.5. A burner according to claim 3 wherein the wall segments extend in thesame general direction as the manifold so that the wall segments foreach wall are arranged one after another away from the manifold.
 6. Aburner according to claim 5 wherein the apertures are slots.
 7. A burneraccording to claim 6 wherein the slots in the face portions of the twowall segments located closest to the manifold are staggered with respectto each other and also with respect to the orifices of the manifold,whereby the air admitted into the combustion chamber through those slotscreates vortices about the combustible gas as that gas is introducedinto the combustion chamber through the orifices.
 8. A burner accordingto claim 2 wherein each of the wall segments is provided with a flangeformed integral with its face portion along the sides thereof and turnedoutwardly away from the combustion chamber; wherein the flanges alongthe juxtaposed sides of adjacent wall segments are joined and constitutethe connecting portions; and wherein the apertures are slots whichterminate in the flanges.
 9. A burner according to claim 6 wherein theconnecting portions on the wall segments are outwardly turned flangesextending along the sides of the face portions; and wherein the slotsextend at least to the flanges.
 10. A burner according to claim 7wherein the slots in adjacent wall segments are staggered relative toone another so that a slot is not continued beyond the wall segment inwhich it is located.
 11. A burner according to claim 1 wherein theopposing walls diverge away from the manifold and are connected at theirsides by sidewalls.
 12. A burner according to claim 8 wherein the slotsterminate at enlarged cutouts formed in the side flanges of the wallsegments.
 13. A burner according to claim 2 wherein the burner isdisposed within an airstream with its combustion chamber openingdownstream; wherein a closure encloses the outwardly presented faces ofthe opposed sidewalls and form combustion air supply plenums therewith;and wherein the air supply plenum are supplied with air from theairstream through at least one air-metering means which opens upstreamin the airstream.
 14. In a duct through which a moving stream of airflows; an improved burner for heating the air flowing in the duct; saidburner comprising a manifold connected to a source of combustiBle gasand having orifices through which the combustible gas is discharged fromthe manifold; opposed combustion chamber walls extending away from themanifold and defining a combustion chamber having one end locateddownstream from the other end relative to the stream of air flowing inthe duct, the opposed combustion chamber walls at the upstream end ofthe combustion chamber being presented adjacent to the manifold onopposite sides of the manifold orifices so that the orifices open intothe combustion chamber, the downstream end of the combustion chamberopening into the duct and facing downstream therein, the combustionchamber walls having apertures therein; outer walls presented outwardlyfrom the combustion chamber walls and forming a closure therewith whichdefines a supply plenum, the supply plenum communicating with thecombustion chamber through the apertures in the combustion chamberwalls; and inlet means associated with the outer walls and defining anopening which faces upstream in the duct and is exposed directly to theairstream therein so that the air flowing in the duct will enter theopening, the opening communicating with the air supply plenum, wherebythe air which enters the opening passes into the plenum from which it isdischarged into the combustion chamber through the apertures on thecombustion chamber walls, the aperture being elongated slots extendingin the same general direction that the combustible gas is introducedinto the combustion chamber, and at least some of the slots in one wallbeing staggered with respect to slots in the opposite wall; the orificesbeing arranged in longitudinally spaced relation along the manifold; theslots which are located in those portions of the opposed combustionchamber walls which are adjacent to the orifices being staggered withrespect to the orifices so that elongated vortices are induced about theaxes of the orifices.
 15. In a duct through which a moving stream of airflows; an improved burner for heating the air flowing in the duct; saidburner comprising a manifold connected to a source of combustible gasand having orifices through which the combustible gas is discharged fromthe manifold; opposed combustion chamber walls extending away from themanifold and defining a combustion chamber having one end locateddownstream from the other end relative to the stream of air flowing inthe duct, the opposed combustion chamber walls at the upstream end ofthe combustion chamber being presented adjacent to the manifold onopposite sides of the manifold orifices so that the orifices open intothe combustion chamber, the downstream end of the combustion chamberopening into the duct and facing downstream therein, the combustionchamber walls having apertures therein; outer walls presented outwardlyfrom the combustion chamber walls and forming a closure therewith whichdefines a supply plenum, the supply plenum communicating with thecombustion chamber through the apertures in the combustion chamberwalls; and inlet means associated with the outer walls and defining anopening which faces upstream in the duct and is exposed directly to theairstream therein so that the air flowing in the duct will enter theopening, the opening communicating with the air supply plenum, wherebythe air which enters the opening passes into the plenum from which it isdischarged into the combustion chamber through the apertures on thecombustion chamber walls, wherein the inlet means comprises at least onemember which is shiftable relative to the outer walls so that the sizeof the inlet opening can be varied.